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lgh1992314:
Godlikeme 写道<div class='quot ...
使用JDBC时Class.forName()的作用 -
lgh1992314:
Class.forName("com.mysql.j ...
使用JDBC时Class.forName()的作用 -
sandaobusi:
nkd2002 写道“我们完全可以用这样一句代替它:”博主这名 ...
使用JDBC时Class.forName()的作用 -
nkd2002:
“我们完全可以用这样一句代替它:”博主这名句话有错误,第二段代 ...
使用JDBC时Class.forName()的作用 -
topcoder_lin:
写的很好!!!!
使用JDBC时Class.forName()的作用
Why doesn't Linux need defragmenting?It's a question that crops up with depressing regularity: Why don't Linux filesystems need to be defragmented?. Here's my attempt at giving a simple, non-technical answer as to why some filesystems suffer more from fragmenting than others. Rather than simply stumble through lots of dry technical explanations, I'm opting to consider that an ASCII picture is worth a thousand words. Here, therefore, is the picture I shall be using to explain the whole thing: a b c d e f g h i j k l m n o p q r s t u v w x y z a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 b 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 j 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 k 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 n 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 u 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 v 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 z 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 This is a representation of a (very small) hard drive, as yet completely empty - Hence all the zeros. The a-z's at the top and the left side of the grid are used to locate each individual byte of data: The top left is aa, top right is za, and bottom left is az. You get the idea, I'm sure. . . We shall begin with a simple filesystem of a sort that most users are familiar with: One that will need defragmenting occasionally. Since both Windows and Linux users make use of FAT filesystems, if only for USB flash drives, this is an important filesystem - unfortunately, it suffers badly from fragmentation. We add a file to our filesystem, and our hard drive now looks like this: a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t a e l e 0 0 0 0 0 0 0 0 0 0 b 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e H e l l o , _ w o r l d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (Empty rows g-z ommitted for clarity) To explain what you see: The first four rows of the disk are given over for a "Table of contents", or TOC. This TOC stores the location of every file on the filesystem. In the above example, the TOC contains one file, named "hello.txt", and says that the contents of this file are to be found between ae and le. We look at these locations, and see that the file contents are "Hello, world" So far so good? Now let's add another file: a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t a e l e b y e . t x t m e z b e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e H e l l o , _ w o r l d G o o d b y e , _ w o r l d f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 As you can see, the second file has been added immediately after the first one. The idea here is that if all your files are kept together, then accessing them will be quicker and easier: The slowest part of the hard drive is the stylus, the less it has to move, the quicker your read/write times will be. The problem this causes can be seen when we decide to edit our first file. Let's say we want to add some exclamation marks so our "Hello" seems more enthusiastic. We now have a problem: There's no room for these exclamation marks on our filesystem: The "bye.txt" file is in the way. We now have only two options, neither is ideal:
To illustrate: Here is approach one a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t a f n f b y e . t x t m e z b e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e 0 0 0 0 0 0 0 0 0 0 0 0 G o o d b y e , _ w o r l d f H e l l o , _ w o r l d ! ! 0 0 0 0 0 0 0 0 0 0 0 0 And here is approach two: a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t a e l e a f b f b y e . t x b t m e z e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e H e l l o , _ w o r l d G o o d b y e , _ w o r l d f ! ! 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 This is why FAT filesystems need defragging regularly. All files are placed right next to each other, so any time a file is enlarged, it fragments. And if a file is reduced, it leaves a gap. Soon the hard drive becomes a mass of fragments and gaps, and performance starts to suffer. And then there is Linux. Which has a different philosophy. Windows filesystems are ideal if you have a single user, accessing files in more-or-less the order they were created in, one after the other. Linux, however, was always intended as a multi-user system: It was gauranteed that you would have more than one user trying to access more than one file at the same time. So a different approach was used. When we create "hello.txt" on a Linux filesystem, it looks like this: a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t h n s n 0 0 0 0 0 0 0 0 0 0 b 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 j 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 k 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 n 0 0 0 0 0 0 0 H e l l o , _ w o r l d 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 u 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 v 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 z 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 And then when another file is added: a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t h n s n b y e . t x t d u q b u 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 j 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 k 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 n 0 0 0 0 0 0 0 H e l l o , _ w o r l d 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 u 0 0 0 G o o d b y e , _ w o r l d 0 0 0 0 0 0 0 0 0 v 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 z 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The cleverness of this approach is that the disk's stylus can sit in the middle, and most files, on average, will be fairly nearby: That's how averages work, after all. Plus when we add our exclamation marks to this filesystem, observe how much trouble it causes: a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t h n u n b y e . t x t d u q b u 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 T O C e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 j 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 k 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 n 0 0 0 0 0 0 0 H e l l o , _ w o r l d ! ! 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 u 0 0 0 G o o d b y e , _ w o r l d 0 0 0 0 0 0 0 0 0 v 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 z 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 That's right: Absolutely none. Windows tries to put all files as close to the start of the hard drive as it can, thus it constantly fragments files when they grow larger and there's no free space available. Linux scatters files all over the disk so there's plenty of free space if the file's size changes. It also re-arranges files on-the-fly, since it has plenty of empty space to shuffle around. Defragging a Windows filesystem is a more intensive process and not really practical to run during normal use. Fragmentation thus only becomes an issue on Linux when a disk is so full that there just aren't any gaps a large file can be put into without splitting it up. So long as the disk is less than about 80% full, this is unlikely to happen. It is also worth knowing that even when an OS says a drive is completely defragmented, due to the nature of hard drive geometry, fragmentation may still be present: A typical hard drive actually has multiple disks, AKA platters, inside it. Let's say that our example hard drive is actually on two platters, with aa to zm being the first and an to zz: a b c d e f g h i j k l m n o p q r s t u v w x y z a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 b 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 j 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 k 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 a b c d e f g h i j k l m n o p q r s t u v w x y z n 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 u 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 v 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 z 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 The following file would be considered non-fragmented, because it goes from row m to row n, but this ignores the fact that the stylus will have to move from the very end of the platter to the very beginning in order to read this file. a b c d e f g h i j k l m n o p q r s t u v w x y z a T O C h e l l o . t x t r m e n 0 0 0 0 0 0 0 0 0 0 b 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 c 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 e 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 f 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 g 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 h 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 j 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 k 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 l 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 m 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 H e l l o , _ w o a b c d e f g h i j k l m n o p q r s t u v w x y z n r l d ! ! 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 p 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 q 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 r 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 t 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 u 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 v 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 w 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 y 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 z 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I hope this has helped you to understand why no defragging software came with your Linux installation. If not, I'm always open to suggestions |
发表评论
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Hello, life !
2010-10-22 19:45 1547If you are alive, you breath. ... -
Logo4me :o)
2009-04-06 21:56 1593.. -
电梯测验
2008-11-28 23:53 1580“要对你的解决方案或是产品或是企业完全了解到一定程度,那 ... -
常用标点符号的英文读法
2008-08-04 14:00 3972.period 句号 ,comma 逗号 :colon 冒 ... -
拥抱Android
2007-11-23 02:03 2187见证一个新事物的诞 ... -
The C10K problem
2007-10-22 19:44 3803The C10K problem 原文链接:http://w ... -
宜宾记忆
2007-09-22 22:03 1325偷得浮生半日闲 ... -
SaaS 软件即服务
2007-07-07 17:15 2195SaaS( Software as a Service ... -
Hype Cycle
2007-07-05 21:58 3300Hype Cycle是对技术的成熟度,大众接受度和商业 ... -
How to Ride the Fifth Wave【转】
2007-06-03 16:31 1717How to Ride the Fifth Wave CHE ... -
背后的路【3】
2007-05-07 16:31 16736 接下来很自然就是面 ... -
背后的路【2】
2007-05-07 16:23 19434 所谓同道中人,专业 ... -
背后的路【1】
2007-05-07 16:11 16230 面对过去,无非就两 ... -
5 Principles For Programming[转]
2007-01-21 02:04 22375 Principles For Programming ... -
长尾理论【转】
2007-01-12 00:20 1839长尾 The long tail 作者: ... -
We are the champions
2007-01-04 00:25 1362I've paid my dues Time after t ... -
I will come to you
2006-10-10 16:15 959When you have no light to guide ... -
杀毒引擎测试
2006-11-07 10:36 1738只要把下面代码复制保存一下,就可以知道你杀毒软件怎么样了,呵呵 ... -
新的开始
2007-01-01 21:33 1352其实写blog是去年暑假的事,那时候觉得应该把自己的一 ...
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包含几项重大改进:模块系统,更好的复制(PSYNC2),对驱逐策略的改进,线程DEL / FLUSH,混合RDB + AOF格式,Raspberry Pi支持作为主要平台,新的MEMORY命令,Redis Cluster支持Nat / Docker,活动内存碎片整理,...
20. dfrg.msc-------磁盘碎片整理程序 21. chkdsk.exe-----Chkdsk磁盘检查 22. devmgmt.msc--- 设备管理器 23. regsvr32 /u *.dll----停止dll文件运行 24. drwtsn32------ 系统医生 25. rononce -p----15秒关机...
5.2.2 磁盘碎片整理 5.2.3 优化虚拟内存设置 5.3 注册表优化设置 5.4 Windows XP瘦身有术 5.4.1 删除不必要的Windows组件 5.4.2 取消休眠功能 5.4.3 删除驱动程序备份 5.4.4 取消系统文件备份 5.4.5 ...
它还将有效负载打印到屏幕上,并向您显示每个操作系统在使用碎片整理引擎重新组装数据包后将如何看待这些数据包。 这是对2012年发布的原始版本的重写,以支持Python3。 重叠片段仍然是个问题吗? 2020年10月16日...
尽管延迟分配、多块分配和 extents 能有效减少文件系统碎片,但碎片还是不可避免会产生。Ext4 支持在线碎片整理,并将提供 e4defrag 工具进行个别文件或整个文件系统的碎片整理。 11. inode 相关特性。 Ext4 支持更...
系统启动的时候会锁定磁盘,所以当启动linux1后共享磁盘被锁定了,linux2就起不来了,因此需要加入disk.locking = "false"。 一般来说,如果是scsi1:0,则n为1,也就是scsi1.sharedBus = "virtual" ,表示所有的bus都...
第22课:磁盘管理之磁盘碎片整理-defrag命令 第23课:磁盘管理之格式化命令-format命令 第24课:磁盘管理之卷标更改命令--label命令 第25课:文件传输FTP命令的讲解(上) 第26课:文件传输FTP命令的讲解(下) 第27...
freede是Linux文件系统的免费碎片整理程序。 它具有使碎片整理算法适应当前文件系统的能力。 包含常规的移动碎片整理程序,并且应适用于所有普通文件系统。
github: https://github.com/ThomasCX/defragfs defragfs 项目针对 Linux 操作系统的文件系统/目录碎片整理,它(目前)是独立于文件系统的,只有 CLI,希望进一步的开发可以带来 GUI和更好的功能。
10.3.5. Oracle碎片整理 53 10.3.5.1. 碎片是如何产生的 53 10.3.5.2. 碎片对系统的影响 53 10.3.5.3. 自由范围的碎片计算 53 10.3.5.4. 自由范围的碎片整理 54 10.3.5.5. 段的碎片整理 54 10.3.6. Oracle系统参数的...
利用本软件可以方便快捷的构建出多层次、多维度、带交叉引用、支持快速查询、层次分明、一目了然的个人知识库, 帮助自己将大量杂乱无章的碎片化知识点重新进行系统化的归纳整理和消化吸收,从而在大脑中建立完整的...
在使用concurrent gc的情况下,防止memory fragmention,对live object进行整理,使memory 碎片减少 h: -XX:CMSInitiatingOccupancyFraction= 指示在old generation 在使用了n%的比例后,启动concurrent collector,...
它基于ext4文件系统中的在线碎片整理ioctl EXT4_IOC_MOVE_EXT,该文件是在Linux内核2.6.31中引入的。 因此,不支持其他文件系统类型或更早版本的扩展文件系统。 e4rat-lite是通过在主e4rat树上实现e4rat-preload-...